The present invention fits in the technical field of the obtainment of plant extracts with different medicinal, cosmetic, dietetic applications, etc.
More especially, the present invention provides a method for obtaining apolar and polar extracts of Curcuma that have important applications as catchers of free radicals and antiageing agents.
Curcumin and other curcuminoids, such as the essential oils obtained from plant extracts of the Curcuma and in general of the Zingiberaceae family, are useful for the treatment and prophylaxis of different diseases. For example, one can cite: EP568,001 (antiviral agents), EP440,885 (antiinflammatory agents), EP319,058 (against loss of hair), EP256,353 (treatment of malabsorption syndromes), U.S. Pat. No. 5,108,750 U.S. Pat. No. 4,906,471, U.S. Pat. No. 4,842,859 platelet antiaggregation agents and anticholesterol agents); WO88/05304 (against hepatitis B and AIDS), WO88/08713 (treatment of neurological disorders), U.S. Pat. No. 4,568,546 (antivenin agent). The antioxodizing and dyeing properties of curcumin and of the derivatives thereof are also known, thus, they are widely used in the food and cosmetic industries as natural preservatives (U.S. Pat. No. 5,266,344, KK KOBE SEIKO SHO).
On the other hand, it is known that the excess of reactive oxygen and free radicals in tissues produces alterations that can lead to premature ageing of cells and the onset of different diseases. Giving the growing concern for this phenomenon, it is not surprising that there are numerous documents about the preparation of plant extracts with antioxidizing effects, catchers of free radicals and therefore useful in the prevention of ageing of cells. However, in the specific case of Curcuma longa extracts the number of documents found is not very large and for the most part they are not patent literature.
Among the bibliographic references of the most interesting patents existing in the data banks, application FR2,655,054 (PACIFIC CHEMICAL) about the cellular protection agents contained in curcuminoids (curcumin, 4-hydroxycinnamoyl (pheruloly)methane, bis (-hydroxycinnamoyl) methane, etc.) obtained from Curcuma longa, ascorbic acid and/or dismutase superoxide (DSO) stands out. Curcuminoids have a known antioxidizing effect, as well as ascorbic acid and DSO that carry out a synergic effect.
On the other hand, the antiinflammatory activity of curcuminoids can also result from their antioxidizing activity. In this sense, application EP550,807 (STEIGERWALD ARINEIMITTELWERK) describes Curcuma longa preparations useful for the treatment of inflammatory diseases associated with the excess production of leukotrienes and prostagalins (Crohn""s disease, bronchial asthma, psoriasis, etc.) According to this document, curcumin carries out its antiinflammatory action on the one hand participating in the reactions of elimination of active oxygen and free radicals and on the other hand by inhibiting the cyclooxygenase and lipooxygenase, enzymes responsible for the synthesis of prostaglandins and leukotrienes respectively.
In connection with the methods of extraction of the polar and apolar fractions of the Curcuma longa rhizomes, they are conventional methods that use usual solvents (liquids in normal conditions) or else liquid CO2 or NO2 or in supercritical conditions, which is likewise usual for the extraction of fragrances and essential from plants xe2x80x9cCarbon dioxide extracted ingredients for fragrancesxe2x80x9d, Flavours and Fragrances O-5M385P, North Albert Road, Reigate, Surrey RH2 9ER, England.)
However, it is a field of noteworthy interest in which it is still desirable to obtain pure extracts, to discover possible new applications of the same in the medical-pharmaceutical fields, in cosmetics, dietetics, etc.
Along these lines, the present invention provides apolar and polar extracts of Curcuma longa with important properties as catchers of free radicals and, consequently, antiageing agents of cells. Likewise, these extracts have shown the capacity to reduce plasma levels of lipid peroxides in humans.
On the other hand, according to the bibliographic data it is known that oxygenated radicals generated in cells are controlled by the cell defense system. The excess generation of such radicals can exceed the protective capacity of the defense system and lead to oxidation of the cell components, proteins, lipids and DNA. These oxidative processes are relevant in the pathogenesis of diseases such as arteriosclerosis and rheumatoid arthritis.
Just as it is indicated in the title, the present invention refers to a method for obtaining apolar and polar extracts of Curcuma and the applications of these extracts.
Plants of the Curcuma genus and, especially, Curcuma longa are tropical plants known from ancient times that belong to the Zingiberaceae family and they originated in Asia. Dried Curcuma rhizomes were already used in Asia as a spice and textile dye. They were also used in popular medicine to treat stomach ailments.
In the last few years, new pharmacological applications have appeared in the scientific literature: antibacterial activity, antiinflammatory activity, lipid peroxidation capacity, antihepatoxic capacity and antitumorigenic capacity.
Curcuma extracts are yellow pigments called curcuminoids, basically comprised of: curcumin (dipheruloylmethane), demethoxycurcumin (hydroxycinnamoylpheruloyl-methane) and bisdeoxycurcimin (dihydroxycinnamoylmethane).
The method of the present invention, for obtaining the apolar extract of Curcuma longa is characterized in that it comprises the following operations:
a) subjecting the previously cut, dried and powdered Curcuma rhizomes to a continuous extraction process for 48 hours, using an organic solvent in a rhizome:solvent ratio of 1:7 weight/volume, carrying out the process in a stationary system to prevent losses of the solvent, for which purpose the temperature of the extraction boiler is adjusted;
b) filtering the extraction mixture resulting from step (a) and evaporating the solvent from the filtrate obtained at reduced pressure obtaining a characteristic brown colored oleoresin as a dry residue;
c) dissolving the oleoresin resulting from step (b) in hot ethyl acetate, in a proportion of 50% w/w and then letting the solution cool down to room temperature for about 24 hours. An orange-colored precipitate that is separated by filtration appears;
d) drying the filtrate coming from the previous step at reduced pressure to obtain a second oleoresin darker than the previous one, whose curcuminoid content is from 20 to 25%;
e) recrystallizing the resulting precipitate in ethyl acetate 50% (w/w) to obtain a solid with a purity in curcuminoids higher than 90%.
On its part, the method of the present invention for obtaining the polar extract of Curcuma longa is characterized in that it comprises the following operations:
a) subjecting the previously cut, dried and powdered Curcuma longa rhizomes to an extraction process with water, keeping them in maceration for about 24 hours at a temperature between 50 and 70xc2x0 C.;
b) filtering the extraction mixture resulting from step (a) and evaporating the water from the filtrate this obtained at reduced pressure to obtain a residue that is a hygroscopic solid corresponding to the polar extract of Curcuma longa. 
Likewise, the method of the present invention is carried out by supercritical extraction, for which purpose the Curcuma rhizome, previously cut, dried and powdered is extracted with ethanol/CO2 and at a pressure of about 260 bar, to obtain the corresponding apolar extract with a purity in curcuminoids of 90%. The apolar extract thus obtained is identical to the one obtained by extraction with solvents according to what is shown by the spectroscopic and chromatographic data thereof. In the same way, but using water as a cosolvent, the polar extract, whose fine layer chromatography totally coincides with that of the extract obtained by maceration in water indicated above, is obtained.
Preferably, obtainment of the above mentioned apolar extract, by supercritical extraction is carried out in the following conditions:
Drying the cut Curcuma longa at a temperature of 50xc2x0 C.;
Grinding the rhizome into particles between 0.xe2x88x921 and 1 mm;
Extracting the Curcuma longa rhizome using ethanol, modified with a small amount of CO2, as a solvent, at 250 bars and 50xc2x0 C.;
Extracting the ethanol present in the oleoresin with CO2 at 280 bars and 50xc2x0 C.;
The apolar and polar extracts of Curcuma thus obtained have a capacity to catch free radicals, specifically, OHxe2x80xa2 hydroxyl and O2xe2x80xa2 superoxide radicals as is shown hereinafter by the studies carried out by the inventors in this regard. Besides, said extracts, as it is also shown hereinafter, have a capacity to reduce the plasma levels of lipid peroxides in human beings. Consequently, they have beneficial effects in pathologies related to cell oxidation such as arteriosclerosis and rheumatoid arthritis.
The present invention also includes compositions and preparations with a capacity to catch free radicals, which are effective against ageing processes, protection of genetic material and antimutagenic capacity. Likewise, it includes compositions and preparations with a capacity to reduce the plasma levels of lipid peroxides.
The cited compositions or preparations contain as active principles the polar or apolar extracts of Curcuma longa rhizome obtained by the method of the invention or mixtures of the same, along with pharmaceutical quality excipients suitable for oral administration.
These oral preparations can come in solid form (powder, tablets, dragxc3xa9es, capsules, etc.) or in liquid form (syrups or suspensions).
In accordance with what has been said above, the present inventors show as a protective agent or catcher of free radicals, aside from the apolar extract of Curcuma longa, which the curcuminoids are in, the aqueous or polar extract of Curcuma longa in which there is no curcumin nor curcuminoid. Besides, the studies carried out by the cited inventors, show that the aqueous extract of Curcuma longa is in itself a strong catcher of free radicals, especially superoxide (O2xe2x80xa2).
The relative application to the reduction of the plasma levels of lipid peroxides is fundamentally based on the capacity to catch free radicals of the cited extracts.
Within the field of study of ageing, it is necessary to evaluate different variables that belong to the scopes of physiology, biochemistry and psychology. The studies directed towards preventive gerontology have lead to the creation of the profile of biological age and life style, that intend to be a tool that evaluates in the strictest and simplest possible way the most sensitive parameters regarding vital habits such as: Pharmacological treatment, tobacco, alcohol, exercise, sleep, perception of one""s own health and stress.
Apart from the life style of the population in general, there are biochemical parameters such as total cholesterol, tricglycerides, glucose, uric acid and HDL/cholesterol, which are considered important in the evaluation of the degree of ageing.
In this sense, due to the large amount of information that it creates, it is interesting to include in the profile of biological age, a biochemical parameter, that can be measured rather easily in peripheral blood: lipid peroxides, resulting from the oxidation by the free radicals derived from oxygen, on the polysaturated fatty acids that form part of the phospholipids of membranes.
This oxidative process frequently exceeds the homeostatic capacity of the cell and there may be an abnormal and uncontrolled oxidation process with massive destruction of the cell membrane. It is known that in homeostasis of peroxidation antioxidants such as beta-carotenes and tocopherols take part. Therefore, it is logical to think that exogenous administration of an antioxidant, can be useful to reestablish this cellular balance.
The present inventors have studied the antioxidizing capacity of pharmaceutical compositions comprised of polar and apolar extracts of Curcuma longa, for their action on the serum levels of malonaldehyde (MDA) in human beings, as an indicator of their blocking capacity of the action of free radicals of the cell membrane. The conclusions obtained from this study are the following:
1. Curcuma longa is a natural extract that reduces the plasma levels of lipid peroxides, which implies a protective mechanism of the cell membrane.
2. It has no toxicity at all: the intake of Curcuma longa for 105 days does not modify the liver and kidney blood tests.
3. The effect at the level of lipid peroxides is rapid: 45 days later a drop of the same was already detected, practically in all decades and in both sexes.
4. The inhibition of lipid peroxides and the catch of free radicals, basic properties of Curcuma longa are one of the grounds on which the theories of ageing are based.